Oscillograph galvanometer



July 9, 1940 J. A. MAURER, JR 2,207,064

OS CILLOGRAPH GALVANOMETER Filed Aug. l0, 1938 2 Sheets-Sheet l as a7 4FIG l l? l2 a4- 38\ /39 Mme@ 444/ 'Y Y Mafer/a/w3o"`\ B2b 23 55 l215INVENTEIR July 9, 1940- J. A. MAUER, JR 2,207,064

OSCILLOGRAPH GALVANOMETR Filed Aug. l0, 1938 2 Sheets-Sheet 2 29 o.@gama/z* ree/ 54 k.Brass l a. www@ INVENTEJR Patented July 9, 1940UNITED STATES PATENT OFFICE OSCILLOGRAPl-I GALVANOMETER John A. Maurer,Jr., New York, N. Y., assignor to The Berndt-Maurer Corp., New York, N.Y., a corporation ol New York This invention relates to deviceswhichtranslate alternating electric current signals into correspondingoscillations of a. beam'of light, and has for its principal object theprovision of an improved oscillograph galvanometer suitable for use inconnection with recording sound on iilm, picture transmission, and thelike.

Other objects of the invention are the provision of an voscillographgalvanometer which lends itself readily to standard manufacture, whichis rugged in structure and of uniform performance over long periods ofservice and which needs no adjustment once it is properly assembled, butwhich at the same time is of improved eiiiciency 1;, in response and `ofimproved fidelity in-translation. These results are substantiallyachieved by employing a small number of elements and adapting as many ofthem as possible to be -formed by punch press operations, by making thewhole structure compact, by inserting in the field magnetic circuit ofthe device an air gap which is easily adjustable, by accuratelycontrolling the length of the air gaps that separate the armature fromthe pole pieces, and by various other features which 'are set forth inthe following description.

'Ihe invention will be better understood when the following descriptionis considered with the accompanying drawings, and its scope will bepointed out in the appended claims.

Referring to the drawings:

Fig. 1 is a. longitudinal section of an oscillograph galvanometeraccording to the invention.

Fig. 2 is a perspective view of certain elements thereof.

FiFig. 3 isan elevation of the left-hand end of g. l. f

Fig. 4 is a section on line 4-4 of Fig. 1.

Fig. 5 is a section on line 26 of Fig. 1.

Fig. 6 shows another oscillograph galvanometer according to theinvention; the shell being broken away, and the elements being shown intop view.

Fig. 7 is an elevation of the right-hand ends of Figs. 1 and 6.

Referring rst to Figs. 1 to 5 inclusive, there is shown a shell lll,containing the other elements of the oscillograph galvanometer. ShellIll is made of magnetic material, for example, of steel, and maypreferably have rectangular sides and square 50 faces as shown. Theinterior Il of shell l0 is cylindrical but has two different diameters,so

that a shoulder I2 is formed within the shell l0. A pair of pole piecesand-2l and a yoke 22,

.magnetically connecting them together, are made 55 up by assemblinglaminae 23, 23, of mag- Aers 24,24,

netic material and of suitable shape, for example, ofA U-shape as shownin Figs. 1 and 2, as a bundle, and inserting them with a press iit intoan aperture 24a of corresponding size in a stack of wash- The laminae 23may preferably consist of silicon steel punchings, and the washers 24are made of non-magnetic material, for example, brass.

The stack of washers 24 is inserted with a press l t into the largerportion of the interior of shell I0 and seated against the shoulder I2therein so as to hold the laminae 23 within the shell l0. The dimensionsof the parts are so chosen that the plane, in which pole pieces 20 and2l' end and which is indicated in Fig. 1 by the broken line 25, is ashort distance inside the plane 0f the face of shell I0, which isindicated in Fig.1 by the line 26; line 26 denoting at the same time theback face of the armature support 4I.

A mounting block 30 of magnetic material is threaded into the oppositeend of shell l0 and is on its outer face, provided with a slot 3| orsimilar means to receive the blade of a screwdriver or the like foradjusting its position within shell I0. The pole 32a of a permanentlymagnetized element 32, conveniently of cylindrical form, is mounted in acorrespondingly shaped recess 33 in the inner face of block 30. 'Ihepermanent magnet 32 may be made of steel or preferably of any one ofseveral magnetic materials now available which have high coercive force,such as 35% cobalt steel or the alloys of aluminum, nickel, and cobalt.

The exposed pole 32h of the magnet 32 is faced by the yoke 22, that is,the bottom end of the bundle of laminae 23, and the distance betweenyoke 22 and pole 32h may be adjusted with cony siderable accuracy byscrewing block 36in or out. Thus, yoke 22 and pole 32b are separated byan adjustable air gap 34, by the adjustment of which the field strengthof the oscillograph galvanometer Vcan readily be controlled.

In a simpliiied arrangement, shown in Fig. 6, a permanent magnet 29 isIixedly mounted within the shell I0 so that its pole 29a is magneticallyconnected to the shell I0. This may be accomplished, for example, bygiving to the magnet 29 a shape somewhat like a mushroom, as shown, andinserting it with a press fit into that end of shell l0 which has thenarrower internal diameter, so that its exposed pole 29h touches orcomes close to yoke 22.l Thus, air gap 34 may be dispensed with or maybe given a denite length,

and a device is obtained which still will yield satisfactory results,though it-.will not give quite as good performance as though theadjustable air gap 34 were provided in the manner described above.

A bi-polar winding 35 is mounted on a suitable support and placed overthe pole pieces 20 and 2l, that is, the arms of the bundle of laminae23. The ends 36 and 3l of the winding 35 leave the shell I0 throughholes 38 and 39, and are connected to the source of the alternatingsignal currents.

On that face of shell I0 near which the pole pieces 20 and 2| terminate,there are provided holes 40, shown in Fig. 5, threaded to receive screwsthat secure the armature support to this face of shell l0.

The armature may be made integral with its support, as shown in Fig. 7,wherein the armature support 4I is a square plate of magnetic material,for example, thin steel, preferably silicon steel. Holes 42 are providedfor the insertion of the screws 40a. that enter the holes 40 on the faceof shell I for securing the support 4I to the shell l0. The armature 43and the two torsion arms 44, 45, on which it is suspended, are obtainedby cutting out from the plate 4l the two apertures 46, 41. A mirror 48is mounted on the side of armature 43 turned away from the pole pieces2D and 2|, or this side of armature 43 may be polished and renderedreflecting by any suitable means, such as plating.

When the support 4l is fastened to the shell l0 the armature 43 issupported so that its ends 50 and 5| are symmetrically located oppositethe poles 52 and 53 of pole pieces 20 and 2l, that is, the unsupportedends of the bundle of laminae 23, when no signal currents are beingapplied to winding 35. The air gaps 54 and 55 separating the ends 50 and5l of the armature 43 and the poles 52 and 53 can be controlled, whenthe shell l0 and the stack of washers 24 holding the laminae 23 havebeen nally assembled, by grinding or lapping the face of shell l0 to aplane surface, and at the same time grin-ding oil the poles 52 and 53,so that their plane indicated by the dotted line 25 in Figs. 1 and 6will be the required distance below the plane of the face of shell l0,indicated by the line 2B in Figs, 1 and 6. 'I'he distance between planes25 and 26 can be measured very accurately by means of a micrometer depthgauge or the like, and this distance once established is not subject toerrors arising from any subsequent assembling operations.

The above description is merely to illustrate certain presentlypreferred embodiments of the invention,` and many other ways of carryingit out will readily suggest themselves to those skilled in the art. 'Iheinvention, therefore, is not to belimited, except in so far as isnecessitated by the prior art and by the spirit of the appended claims.

What is claimed is:

l. An oscillograph galvanometer including a shell of magnetic material;a mounting block of magnetic material threaded into one end of saidshell and adapted to be screwed in and out of said shell; a permanentmagnet having two poles and secured by one of said poles on the innerface of said block; a stack of non-magnetic washers mounted within saidshell; a bundle of U- shaped laminae of magnetic material inserted intosaid stack of washers, the bottom end of said bundle of laminae facingthe other pole of said permanent magnet; a bi-polar winding placed overeach arm of said bundle of laminae; a support of magnetic materialsecured to the other end of said shell; and an armature supported bysaid support opposite the unsupported ends of said bundle of laminae,the ends of said armature and said unsupported ends being separated byair gaps.

2. An oscillograph galvanometer including a. shell of magnetic material;a permanent magnet having two poles and mounted within said shell, oneof said poles being magnetically connected to one end of said shell; apair of pole pieces magnetically connected together an'd held bynon-magnetic means within said shell, their magnetic connection facingthe other pole of said permanent magnet; means for adjusting thedistance between said magnetic connection and said other pole of saidpermanent magnet; a bi-polar winding placed over said pole pieces; asupport of magnetic material secured to the other end of said shell; andan armature supported by said support opposite the poles of said polepieces; the ends of said armature-and said poles of said pole piecesbeing separated by air gaps.

3. In an oscillograph galvanometer a permanent magnet having two poles;a pair of pole pieces magnetically connected together with theirmagnetic connection facing one of said poles; and means for adjustingthe distance between said magnetic connction and said pole.

4. An oscillograph galvanometer including a shell of magnetic material;a permanent magnet havingtwo poles and mounted within said shell, one ofsaid poles being magnetically connected to one end of said shell; a pairof pole pieces magnetically connected together and held by nonmagneticmeans within said shell, their magnetic connection facing and separatedby4 an air gap from the other pole of said permanent magnet; a bi-polarwinding placed over said pole pieces; a support of magnetic materialsecured to the other end of said shell; and an armature supported bysaid support opposite the poles. of sai-d pole pieces, the ends of saidarmature and said poles of said pole pieces being separated by air gaps.

5. In an oscillograph galvanometer a permanent magnet having two poles;and a pair of pole pieces magnetically connected together with theirmagnetic connection facing and being separated by an air gap from one ofsaid poles.

6. An oscillograph galvanometer including a shell of magnetic material;a permanent magnet having two poles and mounted within said shell, oneof said poles being magnetically connected to one end of said shell; apair of pole pieces magnetically connected together and held bynonmagnetic means within said shell, their magnetic connection facingand touching the other pole of said permanent magnet; a bi-polar windingplaced over said pole pieces; a support of magnetic material secured tothe other end of said shell; and an armature supported by said supportopposite the poles of said pole pieces,

vthe ends of said armature and said poles of said pole pieces beingseparated by air gaps,

JOHN A. JR.

